|You might want to be a little more worried|
about melting ice than wine,
but hey, this is a wine blog!
image from niu.edu
As with other fruits, grapes have rising sugar levels and dropping acid levels as they ripen in the warmth of summer. Finding the optimum balance between acid (the tartness) and sugar (that becomes alcohol) is what winemakers strive for.
Grapes will shut down the sugar creation if it gets too hot to conserve water in the vine. Premium wine grapes are grown where there's a cooling influence allowing the vines to rest. That's why California's top wines come from coastal or mountainous areas where the nights and mornings are cooler. The less expensive wines come from the hot inland Central Valley.
If climate change means a warmer growing season for places like coastal California and Oregon the first thing that will be noticed is changes in the wine--not just for one year, but every year. Winemakers will no longer find acids falling to the correct level and having good sugar (and alcohol) levels. If it's warmer and the grapes are picked early to avoid the higher sugars then the colors and flavors in the grapes may not develop fully. You need a certain length to the growing season to get the best wines. This has been a, shall we say, hot topic with grape growers and winemakers for several years. There are certain things a winemaker can do to adjust for climate change, but only up to a point.
The coastal areas have lots of micro-climates. You can find cool climate Chardonnay grown ten miles from warm climate Cabernet Sauvignon, for instance. How will these coastal micro-climates change if the entire planet's climate changes?
The cooler parts of Sonoma County, Carneros and Russian River Valley, are now seeing small, experimental plantings of Bordeaux varieties like Cab Sauv and Cab Franc to see where they might take hold in the coming years. These grapes could always grow in these cooler areas, but generally not produce the highest quality wines as the fruit wouldn't fully ripen.
If the climate heats up grape varieties will be moved to areas that are currently too cool for a particular variety. This isn't too terrible of a situation as grapes varieties have moved around and new ones have been introduced in California and other states over the decades. Pinot Noir and Chardonnay have recently been planted in what were thought extreme conditions along the California coast. Syrah and Sauvignon Blanc came along and replaced grapes like Carignane and French Colombard in the last half of the 20th century.
In the past wine grape varieties have come and gone because of what growers have learned about what can be grown in a particular area or what consumers want. The next move may be because of planet-wide changes.